CFL vs. LED

Standard incandescent light bulbs are among the most profligate energy consumers available, turning more than 90% of the energy they consume into heat rather than light. These old-school bulbs are inexpensive and cast a pleasingly warm light, but their days are numbered.

Compact fluorescent lamps (CFLs) are gradually taking their place. Although they’re more expensive, the cost is coming down and dimmable versions have become available. Bulb life is much longer and, more important, CFLs deliver much more light per watt of electricity than incandescent bulbs.

More recently, light-emitting diodes (LEDs) have emerged as another option. The cost is still well above that for CFLs, but LEDs last a very long time.

Are they worth the extra expense? That’s the question posted by George Lee in a recent Q&A post at GreenBuildingAdvisor, and the topic of this week’s Q&A Spotlight.

Lee is working on a shoestring budget. The house was in such poor repair he was forced to gut it and make extensive repairs. It has no heat, and the banks won’t loan him a dime. Keeping costs down is a high priority.

So don’t waste your money on LEDs

Forget the LEDs, advises GBAGreenBuildingAdvisor.com senior editor Martin Holladay. “Right now, the best LED lamps have approximately the same efficiency as the best CFLs, but they cost about 10 times as much,” Holladay says. “Although LED lamps should last longer than CFLs, you won't see any savings from switching to LEDs — unless the labor cost for changing out a lamp is very high (for example, if the lamp is on a hard-to-reach billboard).”

If Lee goes for reflector-style CFLs in the fixtures, Holladay recommends he read a 2008 report from the Pacific Northwest National Laboratory that includes specs on 16 different lamps.

But LEDs have some advantages

Adam Flowers wouldn’t be so quick to dismiss LEDs. “I’m going to have to respectfully disagree with the previous post,” he writes.

Manufacturers such as Cree and Cooper Lighting offer LEDs that are superior to CFLs, he says. “To be specific, these are not light bulbs, but LED-designed recessed lights,” Flowers says “Obviously you have the longer rated life (50,000 hours in a reputable LED compared to maybe 10,000 in a CFL), but there are a couple of other aspects worth considering.

“The top-notch LED lighting products will be dimmable, while that feature is very costly on CFL products. And light quality (Color Rendering, Color Temperature, direction of light, etc) will be noticeably better under an LED fixture.”

Flowers says that while CFLs are far more efficient than incandescents, “they still convert 20-30% of their energy into heat, so there's the cooling load consideration.” In addition, CFLs contain small amounts of mercury. LEDs don’t.

And the cost difference may not be that significant, says Henri du Pont, who identifies himself as the owner of a company that makes LED products. The best CFLs now cost between $10 and $15, he says, while a good LED is now only about twice that. Rebates may be available, lowering the cost even further. (At its website, Cree offers an energy savings calculator comparing the cost of burning a 65-watt incandescent with a life of 2,000 hours to a 12-watt LED with a 50,000-hour life, concluding the $130 LED fixture pays for itself in less than 18 months.)

“You must also consider use or ‘burn time,’” he adds, “and if instant on at full lumen output and color temperatures are concerns... I can tell you the only reason to go with CFL is if you just don’t have the funds.”

Or, just skip recessed fixtures altogether

James Morgan has yet another idea: don’t use recessed light fixtures at all. “They are the least efficient lighting formal regardless of lamp type,” he writes, “in most situations, incandescent, LED and CFL all deliver better performance in other fixture styles such as ceiling-mount, pendant, track, and floor and table lamps.”

Also, recessed lighting fixtures are a common source of air leaks into attics, Morgan adds. If they are installed, “you need to be obsessive about air-sealing.”

Our expert's opinion

GBA technical director Peter Yost had these thoughts:

The short answer on residential LEDs is, buyer beware. Problems with heat dissipation, color quality, and flicker persist in the less expensive LEDs, so you really have to pay for the better performing LEDs. And some key performance metrics — Correlated Color Temperature (CCT) and Color Rendering Index (CRI) — don’t work well with LEDs at all.

It’s hard to imagine being on a really tight budget and finding room for LEDs, given how fast the market is evolving, how untrustworthy too many manufacturer’s claims are, and how metrics need to catch up to this still rapidly developing technology.

Here are my recommendations:

Don’t buy anything that you have not actually seen in operation—your eye is still a better judge on the light quality LEDs generate than the metrics we currently have for them.

In terms of equipping a new home for more efficient lighting in the future, I’d like to tell you to get set up with GU24 bases that will work with both efficient LEDs and CFLs, but it is not clear whether this will become the standard residential fitting as lighting efficiency standards continue to get tougher.

The biggest takeaway here is that there are numerous options to consider when switching out incandescent lighting. It's extremely important to consider the lighting purpose and room specs to help figure out which option will be best. Both LEDs and CFLs have their pros and cons, especially between different manufacturers and models. Compare these with regards to the space you are retrofitting to come up with the best game plan.

2.
Aug 29, 2011 9:51 PM ET

Edited Aug 29, 2011 9:52 PM ET.

LEDs versus halogens in bathrooms by William Rau

I bought a house with two 60 watt halogen light fixtures in our windowless master bathroom> Here is the simple payback analysis of replacing them with 8 watt (40 watt equivalent) PAR-20 LEDs:.

In the example above the 8 watt, 40 watt equivalent, PAR-20 LEDs produced slightly more and higher quality light than the 60 watt halogens while generating a simple payback of 2.5 years at only 3 hours of use per day.

Rau,
Of course it makes sense to get rid of your power-hungry halogens. But comparing LEDs to halogens is misleading. The other option under consideration in this discussion is CFLs, not halogens. No one has suggested that halogens make sense.

4.
Aug 30, 2011 10:42 AM ET

There are some deals on LEDs by Kevin Dickson, MSME

“Right now, the best LED lamps have approximately the same efficiency as the best CFLs, but they cost about 10 times as much,”

My local Home Depot has a 40W equivalent LED A19 for $17 now. That's probably only 4X as much as the equivalent CFL. So the field is changing quickly.

Another good source for the latest in cheap LED lighting is Sam's Club. Don't expect to be able to buy the same offerings for more than just a few months though. Once they sell out of a style, you may not ever see it again.

CFLs would not fit in my light fixtures, and if they had, the quality of light would have been poor. In addition, CFLs often do not work well or have shortened life expectancy in can or downward facing light fixtures.

I rely mostly on CFLs in my home, but a large number of people dislike them for a variety of reasons (mercury, poor light quality, flicker, etc.). In contrast, LEDs are superior to both CFLs and incandescents in light quality.

Prices on LEDs should drop 15% to 20% per year over the next several years. At a price point of $18, a 120 lumen/watt LED will use 88% less electricity than an incandescent and will have a payback of less than 3 years. By 2013 a mass exodus to LEDs from incandescent stalwarts will begin because if will make economic sense to replace these 19th century relics.

I can attest to the quality of LSG LEDs, which are carried by Home Depot. They produce excellent light.

7.
Aug 31, 2011 2:25 PM ET

Edited Aug 31, 2011 2:32 PM ET.

Missed the advantage of nimble "task" lighting? by Lucas Morton

I think the article missed one potentially important advantage for LED's that transcends their present lower efficacy relative to fluorescents: form

Most fluorescents on the market that I've seen tend to have fairly large form factors for their fixtures, while LED's generally appear more versatile in their applications (from tiny little key ring light to high-end LED sheet panels). Due to their versatility, you can place LED's in remote, recessed, or otherwise hard to light areas. We've seen the adverts on TV-- don't let their pitchman tones and schlocky histrionics dissuade you from pragmatic purpose. I've placed mine in closets, corridors for motion-activated corridor lighting, in recessed corners of cabinets (like at the deep corner of an L-shaped kitchen cabinet). I have a great time obviating the bulk lumens (and wattage) of overhead lights with the grace of just enough LED light just where I need it. By efficacy standards, my cheapo LED's might not be as good, but in overall energy consumption, as well as practicality and cost, they're a clear winner. Their color rendition isn't great either, but it's a lot better than the narrow caves of darkness I had before. To take my descriptions to logical extremes-- what kind of lighting do you think gastroenterologists use for their endoscopies? You better hope it's not a T8! (pardon my puerile guffaws)

And yes, currently this is the realm of do-it-yourselfers and smart consumers, and not anywhere in the ballpark of the design professionals I personally work with. I believe that it somehow strikes many of them as somewhat inelegant. But then, I'm just an unfrozen caveman engineer, and it seems that non-monetary values seem are correlated with the price tags affiliated with their fulfillment.
In the LED lighting world, I'm hoping we're on the cusp of a proliferation of possibility.

8.
Sep 10, 2011 3:49 PM ET

Halogen/led comparison by Aaron Gatzke

Reply to William Rau
The comparison is not apples to apples.
You should compare a 12 watt led to get the equivalent light to your 60 watt halogen.

9.
Sep 15, 2011 6:57 AM ET

How many hours per day? by curtis betts

William Rau highlights one of the key questions in this analysis: How many hours is the light in use? Cree's website calculator defaults to 18 hours/day, resulting in the 18 month payback. But many fixtures in my home are on far far less - say 15 minutes or less in a closet or basement. Cree calculates the payback then at 80+ years!

Incandescents remain my lamp of choice for applications where use is intermittent: entries, closets, basement stairs, guest rooms... CFL where use is continuous for a couple hours at a stretch, and LED if use is near-continuous, and/or instant-on is needed.

10.
Sep 22, 2011 12:26 PM ET

Invest a Little Bit in LED's by Thomas Farwell

We changed over mainly to CFL's a number of years ago - and I would never go back to incandescent.

The exception is the few lights we want dimmable (theater room, living room over-head). We have been slowly changing these over to LED - testing to see if we like it, and metering out the cost.. At the current prices, will they ever pay off? Not really. However, as the technology matures and the markets expand, they will become viable, just like CFL. So I'm willing to buy a few now at higher prices to help fund the businesses to continue with R&D, knowing the future will be better.